Magnetic frequency changer having partial gaps



Sept. 4, 1951 H. J. M CREARY 2,567,115

MAGNETIC FREQUENCY CHANGER HAVING PARTIAL GAPS Filed May 19, 1950 Fl G.l

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o r o INIBUT INVENTOR. HAROLD J. M CREARY ATTORNEY Patented Sept. 4,1951 MAGNETIC FREQUENCY PARTIAL G CHANGER HAVING APS Harold J. McCreary,Lombard, Ill., assignor to Automatic Electric Laboratories, Inc.,Chicago, 111., a corporation of Delaware Application May 19, 1950,Serial No. 183,043

4 4 Claims. (01. 321-68) This invention relates in general to frequencychangers which utilize saturated ferromagnetic cores to produce analternating current having a frequency which is a harmonic orsub-harmonic of the frequency of an alternating current source; and inparticular to improvement in the construction of the magnetic core andthe arrangement of electrical circuits of such irequency changers.

An object of the present invention is to provide a frequency changerutilizing a magnetic cross valve in which a partial gap is inserted tocreate Odd harmonics.

Other objects and features will appear upon a further perusal of thespecification taken in conjunction with the accompanying drawing whichillustrates several embodiments of the invention in the form ofschematic circuit diagrams.

Fig. 1 is a diagrammatic representation of the frequency changer havingintersecting partial gaps in the center of the magnetic cross valvecore.

Fig. 2 is a diagrammatic representation of a frequency changer havingpartial gaps extending diagonally from two intersecting members of themagnetic cross valve core.

In the present invention two coils are wound through opposite diagonalcorners of the magnetic cross valve so that there is no mutualinductance between the respective coils. However. when the magnetic corereaches a degree of saturation a difierential flux is set up to induce avoltage in one of the coils. A partial gap is used in th magnetic crossvalve core to emphasize the odd harmonic rather than the even harmonicwhich would be caused by D. C. saturation.

Referring now to Fig. 1 which shows a magnetic cross valve l. Themagnetic cross valve I herein used may be of the type disclosed inPatent No. 2,445,857, issued on July 27, 1948.'to the present inventorand also in Patent No. 2,461,992, issued on February February 15, 1949,to the present inventor. Primary winding 2 is shown diagonally woundthrough a pair of oppo'site corners of the intersecting members of themagnetic cross valve l. Secondary winding 3 is wound through anotherpair of diagonal corners of the intersecting members or themagneticcrossvalve I andisdispIacedbyQOdegrees from the primary winding.The result, therefare, is that there is no mutual inductance between therespective coils until the magnetic core has reached a degree 01'saturation. A condenser t is included in the secondary circuit to tunthe A partial gap 9 is shown at the center of the magnetic cross valvecore-l and is positioned in a plane parallel to that of the primarywinding and extends in a direction from one corner to the oppositediagonal corner. Another partial gap I0 is shown at the center of themagnetic cross valve core I and is perpendicular to the partial gap 9.The partial gap In extends between the other pair of diagonal cornersfrom which partial gap 9 is extended. The function of the partial gap isto emphasize the odd harmonics. In magnetic circuits the gap will have adifferent flux density than the metallic core structure. Therefore, at adegree of saturation, a differential flux is set up at the center of themagnetic cross valve to induce a voltage in the secondary winding.

An input alternating current voltage is fed to the primary winding 2.The current flow in the primary winding produce an alternating flux inthe core I. A voltage is induced in the secondary winding Sin a mannerpreviously described. The output signal of the secondary winding is anodd harmonic.

Referring now to Fig. 2 which shows a magnetic crossvalve 5. Themagnetic cross valve 5 herein used may be of the type disclosed inPatent No. 2,461,992, issued on February 15, 1949, to the presentinventor and also in Patent No. 2,445,857,

issued on July 27, 1948, to the present inventor.

A primary winding 6 is wound through a pair of opposite diagonal cornersof the magnetic cross valve 5. A secondary winding 1 is wound throughthe opposite pair of diagonal corners of the magnetic cross yalve 5 andis displaced degrees from the primary winding. A condenser I2 isincluded in the secondary circuit to tune the secondary circuit to thedesired output frequency. A partial air gap 8 is shown extending in adiagonal direction from the lower left-hand corner of the intersectionto a point of close proximity to the-center of the magnetic cross valve5. Another partial gap H is shown extending downward from th upperright-hand corner of the intersection and is extended in close proximityto the center of the magnetic cross valve core 5. The partial gaps shownin Fig. 2 are eflective on only one winding in much the same way assuperimposed D. C. flux would be effective on only one winding. It istherefore possible to produce 20 cycles from a 60 cycle input or it ispossible to produce cycles from a 60 cycle input. The

desired output frequency is produced by changing the size of thecondenser I! so as to tune the secondary circuit to the desired oddharmonic.

secondarycircuittotbedeliredoutputi'requency. uThepartialgapsinFig.2alsoemphasizetheodd harmonics, when a degree ofsaturation is reached in the magnetic core 5. The partial gaps willproduce a flux differential to induce a voltage in the secondary windingI, since the flux density of the air gap is different form the fluxdensity of the ferromagnetic substance used to form the core of amagnetic cross valve 5. The operation is similar to that described inreferenc to Fl .1.

although I have described my invention with a certain degree of'particularity, it should be understood that the present disclosure hasbeen made only by way of example and that numerous changes in thedetails of construction and arrangement of parts may be resorted towithout departing from the spirit and scope of the invention ashereinafter claimed.

What is claimed is:

1. In a frequency changer, a magnetic core structure having twointersecting members, a primary winding wound through opposite diagonalcorners of the intersection, a source of current for energizing saidprimary winding to provide the input signal, a secondary circuit tunedto the desired output signal and wound through the other oppositecorners of said intersection, and said magnetic core having partial gapsat the general area of core saturation to provide a flux differential insaid core whereby an alternating current is induced in said secondarycircuit having a frequency which is integrally related to the frequencyof said source.

2. In a frequency changer, a magnetic core structure having twointersecting members, a primary winding wound through a pair of oppositediagonal corners of the intersection, a source of current connected tosaid primary winding for providing an input signal, a secondary circuittuned to a desired odd harmonic and wound through the other pair ofopposite comers of said intersection, and said magnetic cor havingpartial gaps intersecting at the center of said magnetic core to providea flux difierential in said core whereby an alternating current isinduced in said secondary circuit having a frequency which is an oddharmonic of the jrequency of said source.

3. In a frenquency changer, a magnetic core structure having twointersecting members to form opposite diagonal corners, a primarywinding wound through a pair of opposite diagonal corners of theintersection, a source of current connected to said primary winding forproviding an input signal, a secondary winding tuned to a desiredharmonic and wound around said magnetic core so as to be at right anglesto said primary winding, an output circuit connected to said secondarywinding, and said magnetic core having partial gaps extending from apair of opposite diagonal corners to provide a flux differential in saidmagnetic core whereby an alternating current is induced in saidsecondary winding having a frequency which is integrally related to thefrequency of said source t be delivered to said output circuit.

4. In a frequency changer, a magnetic core structur having intersectingmembers, a primary winding wound through opposite diagonal cornersof theintersection, a source of current for energizing said primary winding toprovide the input signal, a secondary circuit tuned to the desiredoutput signal and wound through the other opposite corners of saidintersection, said magnetic cores having partial gaps angularly disposedwith respect to said intersecting members at the intersection of thecore members to provide a flux differential in said core whereby analternating current is induced in said secondary circuit having afrequency which is integrally related to the frequency of said source.

HAROLD J. MCCREARY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,118,935 Joly Dec. 1, 19141,731,616 Flehr Oct. 15, 1929 2,309,586 Haines Jan. 26, 1943 2,455,078McCreary Nov. 30, 1948

